This invention relates generally to fluid separations, and more particularly to expanders and turbo-compressors operating into the low temperature region generating liquid phases and solid phases (condensed phases) that require removal. Removal of these condensed phases is accomplished by separation equipment that is an added component to a process system. Typically these separators are large and add cost, weight and volume to the process system. Centrifugal separators may be used to decrease the weight and volume, but added cost and complexity result from the requirements for a separate casing, shaft, seals and bearings.
There is need for centrifugal separation means for condensed phases that is integrated into the expander or turbo-compressor (rotating machinery). There is also need for such separation means wherein a separator member either is rotating with the rotating machinery or that is stationary.
Further, various methods have been used to chill gases by expansion to remove the resulting condensed phase, and to compress the remaining dry gas. The least efficient expansion method is a Joule-Thomson valve. The most efficient method is a near isentropic nozzle. A commonly used method which has an efficiency in between these methods is a turbo expander. The higher the expansion efficiency the more liquid is formed during the expansion. Subsequent compression of the remaining dry gas results in the lowest possible dew point.
In the past, the use of a nozzle for the complete expansion has been impractical. The friction loss in a stationary wall separator can be quite large. The subsequent heating of the separated liquid can result in vaporization and more moisture in the gas. However, with the use of a rotating surface the friction loss can be minimized resulting in maximum moisture removal from the gas. There is need for process and apparatus employing a nozzle and rotating surface separator, operating to maximize the liquid removal from a chilled gas stream and to compress the remaining dry gas by utilizing the head imparted during the expansion process.
It is a major object of the invention to provide an improved method for producing and separating liquid from gas, in a flow stream, the method including the steps:
a) expanding the flow stream at a first zone to reduce flow stream pressure and increase flow stream velocity,
b) centrifugally separating liquid from gas in the expanded flow stream, in a second zone,
c) and increasing the pressure of the gas, from which liquid has been separated, by converting kinetic energy of the gas into pressure, at a third zone.
As will be seen, a rotary apparatus may be provided for receiving the flow stream to expand same, at the first zone.
It is another object to provide a flow passage forming the second zone and within which the expanded flow stream swirls for centrifuging liquid outwardly toward a passage wall, and for conducting gas in the flow stream toward the third zone.
Further objects include provision of the first and third zones as rotary zones; provision of the second zone to include a rotary wall toward which liquid is centrifuged; provision of the second zone to include a non-rotating wall toward which liquid is centrifuged; provision of one of the first and third zones as a rotary zone; and provision for coupling the first and third zones, to rotate together.
It is a further object to maximize the liquid removal from a chilled fluid stream, and to compress the remaining dry gas, by utilization of the velocity head imparted during the fluid expansion process. The fluid may consist of a gas.
These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: